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These formulas [14] [15] [16] are known respectively as Fresnel's sine law and Fresnel's tangent law. [17] Although at normal incidence these expressions reduce to 0/0, one can see that they yield the correct results in the limit as θ i → 0 .
The lens is produced in Canon EF mount, Nikon F-mount, Pentax K mount, Sigma's own SA mount, and the Sony/Minolta AF Mount varieties, all have the same optical formula. Since the lens covers full-frame sensors and includes an ultrasonic autofocus motor, it is fully compatible with most DSLRs on which it can be mounted physically.
Visulization of flux through differential area and solid angle. As always ^ is the unit normal to the incident surface A, = ^, and ^ is a unit vector in the direction of incident flux on the area element, θ is the angle between them.
Notable features include the company's second in-house ring-type ultrasonic motor with 1.3x the torque of the Pentax D FA* 50mm lens for fast autofocus, full dust and water resistance with eight sealings and an advanced optical formula for high-resolution images with smooth bokeh.
In optics, the Fraunhofer diffraction equation is used to model the diffraction of waves when plane waves are incident on a diffracting object, and the diffraction pattern is viewed at a sufficiently long distance (a distance satisfying Fraunhofer condition) from the object (in the far-field region), and also when it is viewed at the focal plane of an imaging lens.
The f-number N is given by: = where f is the focal length, and D is the diameter of the entrance pupil (effective aperture).It is customary to write f-numbers preceded by "f /", which forms a mathematical expression of the entrance pupil's diameter in terms of f and N. [1]
Distances in the thin lens equation. For a lens of negligible thickness, and focal length f, the distances from the lens to an object, S 1, and from the lens to its image, S 2, are related by the thin lens formula: + =.
For a single lens surrounded by a medium of refractive index n = 1, the locations of the principal points H and H ′ with respect to the respective lens vertices are given by the formulas = ′ = (), where f is the focal length of the lens, d is its thickness, and r 1 and r 2 are the radii of curvature of its surfaces. Positive signs indicate ...